1. Technical Field
The present invention relates to a vehicle wheel suspension arrangement. More particularly, the invention is related to an independent rear wheel suspension for a driven or non-driven rear wheel of a motor vehicle.
2. Background Information
In vehicles such as passenger cars, various types of suspension systems can be used for the vehicle wheels. These wheel suspensions are designed in a known manner that permits attachment and spring suspension of all the wheels of the vehicle, thereby improving both the comfort of the passengers in the vehicle and the vehicle""s road-handling properties, while increasing the service life of the vehicle. A number of different types of wheel suspensions are already known and included in systems such as rigid or independent wheel axles. If required, these wheel suspensions can be supplemented with spring elements, shock absorbers and other components. Additionally, link arms are often used to take up forces and connect the vehicle""s wheels to its bodywork. Further, stabilizers may also be used to reduce excessive pitching movements of the vehicle.
A conventional rigid rear axle wheel suspension is a robust and effective construction that also maintains a constant track width (i.e., a constant distance between those points where the opposing side rear wheels are in contact with the road surface). However, the rigid rear axle tends to transmit, at least to some extent, the movements of the wheel(s) of one side to the wheel(s) of the other side. For this reason, an independent rear wheel suspension is often used. The independent rear suspension is designed so that the wheels are able to spring independently of each other, which is advantageous with regard to the comfort of the ride. Further, in an independent rear wheel suspension, various link elements are used to maintain the desired track width, camber angle and toe-in angle of each wheel. An independent rear wheel suspension also permits less unsprung weight while providing more space for, for example, the gasoline tank and trunk.
An independent rear wheel suspension can be constructed such that it provides a certain degree of softness in the longitudinal direction of the vehicle, ire., force-absorbing characteristics in the longitudinal direction. This, in turn, can be used to satisfy the comfort of the passengers in the vehicle. The rear wheel suspension can also be constructed with a high xe2x80x9cwindupxe2x80x9d strength, i.e., it counters the tendency of the wheel-bearing housing to twist during braking of the vehicle.
U.S. Pat. No. 4,828,279 (xe2x80x9cthe xe2x80x3279 patentxe2x80x9d) discloses an independent rear wheel suspension for a motor vehicle. The rear wheel suspension according of the xe2x80x3279 patent includes a lower link arm and an upper link arm. Together, both arms connect a wheel-bearing housing to a vehicle bodywork. The wheel-bearing housing is also elastically connected to the lower link arm via a further link element. By doing so, the wheel suspension has an effective force absorption and takes up little space.
Still, the above mentioned arrangement and other similar systems have difficulty in achieving at the same time both a high degree of longitudinal softness and a high windup strength. Further, with know rear wheel suspensions it is difficult to obtain a wheel suspension that reliably maintains a predetermined toe-in angle of the wheel in question, even under the effect of force, for example, upon sharp braking of the vehicle.
Accordingly, there is a need for a vehicle wheel suspension arrangement that is able to achieve both a high degree of longitudinal softness and a high windup strength. Further, there is a need for a vehicle wheel suspension arrangement that reliably maintains a predetermined toe-in angle of the wheel in question, even under the effect of force.
The object of the present invention is to provide an improved rear wheel suspension arrangement in a motor vehicle. In particular, the arrangement permits a high degree of longitudinal softness and high windup strength. This object is achieved by means of an arrangement having a wheel-bearing housing, a lower link arm able to connect the bodywork of the motor vehicle and a lower part of the wheel-bearing housing, and an upper link arm able to connect between the vehicle bodywork and an upper part of the wheel-bearing housing. The invention additionally includes a further connection between the vehicle bodywork and the wheel-bearing housing, and a coupling link that is substantially rigid in the vertical connection and able to connect the further connection and the lower link arm.
The invention affords a number of advantages compared to conventional systems for independent rear wheel suspensions. First, the invention satisfies the requirements for high longitudinal softness and windup strength, thereby providing a high degree of comfort for the passengers in the vehicle while effectively counteracting torsion of the wheel-bearing housing during braking. In addition, the further connection ensures that a correct toe-in angle for the wheel can be defined and maintained. This can be accomplished in one embodiment wherein the further connection is a bar that is dimensioned and arranged so that the predetermined toe-in angle of the wheel is defined and maintained. The invention also permits compact packing.
According to a preferred embodiment of the invention, use is made of a spring element in the form of a leaf spring. This spring element is fixed in the lower link arm and is arranged extending substantially transverse to the longitudinal direction of the vehicle. The leaf spring thereby replaces a conventional helical spring. This leaf spring can additionally provide for stabilization, thereby replacing a conventional stabilizer.
In another embodiment, the lower link arm may be substantially H-shaped and have at least four attachment points. Two of the attachment points can be connected to the vehicle bodywork, another attachment point can be connected to the wheel-bearing housing, and another attachment point can be connected to the coupling link. The further connection may be arranged so that it extends under the lower link arm along an imaginary line between one of the attachment point connected to the vehicle bodywork and the attachment point connected to the coupling link.
In other embodiments, the coupling link can have a substantially vertical extent. The above arrangement can also include a leaf spring that extends substantially transverse to the longitudinal direction of the vehicle. The leaf spring may be fixed in the lower link arm. The leaf spring can be designed with stabilizing properties.
The above arrangement may also include a shock absorber that can be secured between the vehicle bodywork and a point on the underside of the lower link arm. The arrangement can be such that the shock absorber runs freely through a hole in the lower link arm.
The wheel suspension arrangement described can be designed with a predetermined rearward inclination in relation to a vertical plane through the center of the wheel. In doing so, the tendency for the rear portion of the bodywork to lift and drop can be canceled out upon braking and acceleration of the vehicle.